staging: r8188eu: handle errors from ReadAdapterInfo8188EU

staging: r8188eu: handle errors from ReadAdapterInfo8188EU

Update ReadAdapterInfo8188EU to return 0 for success or a negative
error code. If rtw_read8 fails, we can just relay the error it returns.

Update rtw_usb_if1_init to check the return value from
ReadAdapterInfo8188EU. For now, rtw_usb_if1_init does not yet pass errors
from ReadAdapterInfo8188EU on to its caller.

Suggested-by: Pavel Skripkin <paskripkin@gmail.com>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220730143939.671951-2-martin@kaiser.cx
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>